This invention relates generally to horseshoes and more particularly to a horseshoe which is compliant with the relative movements of the hoof of a horse.
Horseshoes have been used for centuries in order to protect the horse""s foot and to enhance performance. Most horseshoes in use today are made of metal such as steel, aluminum alloys, and rarely, stainless steel or titanium. Aluminum alloys are most commonly used today in racing and are characterized by relatively low weight and expense. Horses engaged in training or racing are commonly reshod every four to five weeks. This is done in consideration for the wear incurred by the horseshoes, but also by the desire to maintain healthy geometry with respect to the configuration of the foot and so facilitate optimal biomechanics, or way of going.
The surfaces on which horses train and perform also vary widely. Horses frequently train and compete on grass, sand, cinder, crushed stone, and sometimes on packed surfaces which nearly approach the hardness of asphalt or cement. The hardness of the training or racing surfaces can greatly increase the effective rate of loading, thus the shock and vibration, e.g., the peak g forces which the horse will experience. Such will necessarily influence the nature of the waveform and the primary frequencies of shock and vibration transmitted to a horse""s anatomy. These factors can directly affect a horse""s efficiency, athletic performance and the amount of trauma that will be experienced.
While the characteristic biomechanics or way of going of horses can vary, e.g., as between Standardbreds and Thoroughbreds, or due to different gaits, such as running, jumping, walking, etc., what normally happens as a horse""s foot and hoof impact the ground is that the back of the foot touches first, then the foot flattens and slides anteriorly skating across the surface. In particular, this is true of a horse""s rear foot. Then the rear portion of the foot is loaded and deflection takes place. This will generally cause the foot to rotate backwards at the heel. The foot will then rotate forwards and recover to a relatively neutral position. Subsequently, the foot rapidly rotates forwardly and about a rocker point located between the geometric center of the foot and a short distance behind the anteriormnost area of the toe as the foot breaks over and toe-off takes place, thus ending the ground support phase and beginning the flight phase.
The heel of a horse""s foot normally strikes the ground slightly before the toe, and this results in immediate heel expansion due to the action of the frog. As the frog is forced upward, the frog stay acts as a wedge in the digital cushion. This forces the digital cushion to expand, primarily in the outward direction because it is confined by structures of the foot in the dorsal, volar, and proximal directions. After the hoof is lifted from the running surface, the heel areas contract.
Furthermore, it is known that in the unshod natural state, a horse""s foot and hoof will flex and slightly widen when it is loaded. The use of relatively rigid metal or aluminum horseshoe substantially prevents this natural movement and so tends to reduce both the effective size, and the shock and vibration absorbing capability of a horse""s foot. A steel horseshoe is known to be more flexible in this regard than an aluminum or titanium horseshoe. It is believed that the occurrence of hoof cracks is sometimes caused by the flexing and widening action of the foot and hoof working against the nails associated with a substantially inflexible horseshoe.
One of the challenges encountered when attempting to reduce the rate of loading, and attenuate the shock and vibration experienced by a horse is posed by the fact that a horse is a rather large animal, e.g., commonly weighing between 800-1400 pounds, and when running at speeds between 30-40 miles per hour, a load exceeding 15,000 pounds can be placed upon a horse""s leg. Accordingly, approximately 2600 pounds per square inch can be placed upon a typical horseshoe having roughly 6.5 square inches of working surface. When running on a hard race track, the entire duration of the impact event can be as short as 1.5 milliseconds, and over 350 peak g""s can then be experienced.
The typical metal horseshoes restrict the natural expansion and contraction of the hoof of a horse in motion and can cause increased stress in the hoofs and legs of a horse in motion.
The foregoing illustrates limitations known to exist in present horseshoes. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the present invention, this is accomplished by providing a horseshoe having at least two hinges, a toe area, two heel areas and two quarter areas. The at least two hinges are positioned to allow expansion and relaxation of the horseshoe in compliance with the hoof of a horse in motion. Preferably, the hinges are positioned in the quarter areas of the horseshoe and have a tapered shape with the wide end of the taper being towards the interior of the horseshoe.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.